One fundamental purpose of a nut-and-bolt fastener is to apply a predictable amount of compression to materials fastened. It is commonly assumed that the nut and bolt follow idealized screw mechanics. That is, it is assumed that knowledge of the torque applied to the bolt, when considered with other factors (such as thread pitch and thread friction) gives an indication of the compression supplied by the bolt. However, in practice, the actual compression supplied by the bolt can deviate by as much as 50% from the value calculated based on these assumptions. Numerous factors cause this deviation and include the following. A particular bolt may have been annealed differently than another bolt, with the result that the particular bolt is more easily stretched. Thus, a given torque will cause less compression by the bolt than expected. Also, different frictional characteristics of the threads of the bolt, such as lubrication or the lack of it, corrosion, etc., introduce forces which the applied torque must overcome but which do not contribute to bolt extension. Further, binding of other portions of the bolts may occur, such as between the bolthead and the material itself. Therefore, numerous factors prevent a bolt from behaving as an ideal screw mechanism with the result that the compression provided by the bolt cannot be accurately predicted by measurement of torque alone. Accurate bolt tensioning is important to the gas turbine engine industry, where bolts which fasten engine components together must be precisely tensioned.